:root {
            --bg-color: #050b12;
            --container-bg: #0a1420;
            --card-bg: #101d2c;
            --border-color: #1c2f42;
            --accent-teal: #2dd4bf;
            --accent-gold: #facc15;
            --accent-red: #f87171;
            --accent-green: #4ade80;
            --text-primary: #e4edf5;
            --text-secondary: #6d8299;
            --font-display: 'Space Grotesk', sans-serif;
            --font-mono: 'IBM Plex Mono', monospace;
            --glow-color: rgba(45, 212, 191, 0.2);
            --shadow-color: rgba(0, 0, 0, 0.65);
            --panel-sunken: rgba(0, 0, 0, 0.3);
            --canvas-bg: #050b12;

            /* Live Outbreak Simulator theming — every canvas color is a
               themed token, never a hardcoded hex read at draw time, and
               each is restated explicitly in the light-mode block below
               (var-of-var does not reliably re-track across themes). */
            --grid-color: #16293a;
            --axis-color: var(--accent-teal);
            --graph-text-color: var(--text-secondary);
            --curve-color: var(--accent-gold);
            --target-curve-color: rgba(248, 113, 113, 0.55);
            --playhead-color: rgba(228, 237, 245, 0.35);
            --strip-bg-color: rgba(0, 0, 0, 0.22);
            --dot-healthy-color: #2c4a5e;
            --dot-healthy-border: #3d6580;
            --dot-infected-color: #f87171;
            --dot-infected-glow: rgba(248, 113, 113, 0.6);

            /* Shared kit mapping */
            --kit-accent: var(--accent-teal);
            --kit-accent-ink: #00201a;
            --kit-accent-glow: var(--glow-color);
            --kit-surface: var(--card-bg);
            --kit-border: var(--border-color);
            --kit-input-bg: var(--container-bg);
            --kit-error: var(--accent-red);
        }

        /* TRUE LIGHT THEME — bright clinical-white lab report look,
           not a second dark palette. Panels sit in the #f2f6f8–#ffffff
           range with dark, readable text and softer accent tones. */
        body.light-mode {
            --bg-color: #f1f6f6;
            --container-bg: #ffffff;
            --card-bg: #f6faf9;
            --border-color: #c9dcd8;
            --accent-teal: #0d9488;
            --accent-gold: #b45309;
            --accent-red: #dc2626;
            --accent-green: #15803d;
            --text-primary: #0c1f22;
            --text-secondary: #4a6763;
            --glow-color: rgba(13, 148, 136, 0.12);
            --shadow-color: rgba(10, 40, 40, 0.1);
            --panel-sunken: rgba(12, 60, 55, 0.05);
            --canvas-bg: #f6faf9;

            /* Live Outbreak Simulator theming (light) — redeclared in full,
               same reasoning as --kit-* below: never rely on a var-of-var
               inheriting its override, restate every token explicitly. */
            --grid-color: #d8e6e3;
            --axis-color: var(--accent-teal);
            --graph-text-color: var(--text-secondary);
            --curve-color: var(--accent-gold);
            --target-curve-color: rgba(220, 38, 38, 0.45);
            --playhead-color: rgba(12, 31, 34, 0.25);
            --strip-bg-color: rgba(12, 60, 55, 0.06);
            --dot-healthy-color: #cfe3df;
            --dot-healthy-border: #9fc4bd;
            --dot-infected-color: #dc2626;
            --dot-infected-glow: rgba(220, 38, 38, 0.4);

            /* Shared kit mapping (light) — redeclared in full: a custom
               property whose value is var(--other-var) does not reliably
               re-track that other var's light-mode override, so every
               --kit-* token must be restated here, not just the ink. */
            --kit-accent: var(--accent-teal);
            --kit-accent-ink: #000000;
            --kit-accent-glow: rgba(13, 148, 136, 0.18);
            --kit-surface: var(--card-bg);
            --kit-border: var(--border-color);
            --kit-input-bg: var(--container-bg);
            --kit-error: var(--accent-red);
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
            transition: background-color 0.25s ease, color 0.25s ease, border-color 0.25s ease;
        }

        body {
            background-color: var(--bg-color);
            color: var(--text-primary);
            font-family: var(--font-mono);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            padding: 16px;
        }

        .top-controls {
            position: fixed;
            top: 18px;
            right: 22px;
            z-index: 1000;
        }

        .theme-toggle-btn {
            background: var(--container-bg);
            color: var(--text-primary);
            border: 2px solid var(--border-color);
            padding: 8px 16px;
            border-radius: 6px;
            font-family: var(--font-mono);
            font-weight: 700;
            font-size: 0.85rem;
            cursor: pointer;
            box-shadow: 0 4px 12px var(--shadow-color);
            display: flex;
            align-items: center;
            gap: 6px;
        }

        .theme-toggle-btn:hover {
            border-color: var(--accent-teal);
            color: var(--accent-teal);
        }

        .lab-container {
            width: 100%;
            max-width: 1000px;
            background: var(--container-bg);
            border: 2px solid var(--border-color);
            border-top: 5px solid var(--accent-teal);
            border-radius: 10px;
            padding: 28px;
            box-shadow: 0 16px 40px var(--shadow-color);
            min-height: 600px;
            display: flex;
            flex-direction: column;
            justify-content: space-between;
        }

        .lab-title {
            font-family: var(--font-display);
            font-size: 1.75rem;
            font-weight: 700;
            color: var(--accent-teal);
            text-align: center;
            letter-spacing: 0.5px;
            margin-bottom: 4px;
        }

        .lab-subtitle {
            font-family: var(--font-mono);
            text-align: center;
            color: var(--text-secondary);
            font-size: 0.88rem;
            margin-bottom: 20px;
            letter-spacing: 0.5px;
            text-transform: uppercase;
        }

        .hud-status-bar {
            display: flex;
            justify-content: space-between;
            align-items: center;
            background: var(--panel-sunken);
            border: 1px solid var(--border-color);
            padding: 12px 18px;
            margin-bottom: 20px;
            font-family: var(--font-mono);
            border-radius: 8px;
            flex-wrap: wrap;
            gap: 10px;
        }

        .hud-item {
            display: flex;
            flex-direction: column;
        }

        .hud-label {
            font-size: 0.72rem;
            color: var(--text-secondary);
            text-transform: uppercase;
        }

        .hud-value {
            font-size: 1.05rem;
            font-weight: 700;
            color: var(--accent-teal);
        }

        .meter-container {
            width: 150px;
            height: 12px;
            background: var(--border-color);
            border-radius: 6px;
            overflow: hidden;
            margin-top: 4px;
        }

        .meter-fill {
            height: 100%;
            width: 100%;
            background: var(--accent-green);
            transition: width 0.3s ease, background-color 0.3s ease;
        }

        .arena-grid {
            display: grid;
            grid-template-columns: 400px 1fr;
            gap: 22px;
            align-items: start;
        }

        @media (max-width: 860px) {
            .arena-grid {
                grid-template-columns: 1fr;
            }
        }

        .canvas-wrapper {
            position: relative;
            width: 100%;
            max-width: 400px;
            height: 340px;
            margin: 0 auto;
            background: var(--canvas-bg);
            border: 2px solid var(--border-color);
            border-radius: 8px;
            box-shadow: inset 0 0 20px rgba(45, 212, 191, 0.05);
        }

        canvas {
            display: block;
            width: 100%;
            height: 100%;
        }

        .terminal-panel {
            background: var(--card-bg);
            border: 1px solid var(--border-color);
            border-radius: 8px;
            padding: 20px;
            display: flex;
            flex-direction: column;
            justify-content: space-between;
            min-height: 340px;
        }

        .scenario-box {
            background: var(--panel-sunken);
            border: 1px solid var(--border-color);
            border-left: 3px solid var(--accent-teal);
            padding: 14px 18px;
            margin-bottom: 16px;
            border-radius: 6px;
        }

        .scenario-title {
            font-family: var(--font-mono);
            font-size: 0.72rem;
            color: var(--accent-teal);
            text-transform: uppercase;
            letter-spacing: 1px;
            margin-bottom: 6px;
        }

        .scenario-prompt {
            font-family: var(--font-display);
            font-size: 1.08rem;
            line-height: 1.5;
            font-weight: 600;
        }

        .coord-control-group {
            display: flex;
            flex-direction: column;
            gap: 14px;
            margin-bottom: 16px;
        }

        .slider-row {
            display: flex;
            align-items: center;
            gap: 12px;
            font-family: var(--font-mono);
        }

        .slider-label {
            width: 90px;
            font-weight: 700;
            color: var(--accent-teal);
            font-size: 0.9rem;
        }

        .coord-slider {
            flex: 1;
            accent-color: var(--accent-teal);
            cursor: pointer;
        }

        .coord-val-display {
            width: 54px;
            text-align: right;
            font-size: 1.05rem;
            font-weight: 700;
        }

        .narrator-line {
            font-family: var(--font-mono);
            font-size: 0.82rem;
            font-style: italic;
            color: var(--accent-gold);
            text-align: left;
            margin-bottom: 14px;
            min-height: 18px;
        }

        .canvas-legend {
            font-family: var(--font-mono);
            font-size: 0.68rem;
            color: var(--text-secondary);
            text-align: center;
            margin-top: 8px;
            max-width: 400px;
        }

        .input-row {
            display: flex;
            align-items: center;
            gap: 12px;
            font-family: var(--font-mono);
        }

        .param-input {
            flex: 1;
            font: inherit;
            font-weight: 700;
            font-size: 1rem;
            text-align: right;
            padding: 8px 12px;
            border-radius: 6px;
            border: 2px solid var(--border-color);
            background: var(--panel-sunken);
            color: var(--text-primary);
            outline: none;
        }

        .param-input:focus {
            border-color: var(--accent-teal);
            box-shadow: 0 0 0 3px var(--glow-color);
        }

        .match-quality {
            font-family: var(--font-mono);
            font-size: 0.85rem;
            font-weight: 700;
            text-align: center;
            min-height: 20px;
            margin-top: 2px;
        }

        .fire-btn {
            background: var(--accent-teal);
            color: #00201a;
            border: none;
            padding: 14px;
            font-family: var(--font-display);
            font-size: 1rem;
            font-weight: 700;
            letter-spacing: 1px;
            text-transform: uppercase;
            cursor: pointer;
            border-radius: 6px;
            box-shadow: 0 4px 14px var(--glow-color);
            transition: transform 0.15s ease, opacity 0.15s ease;
            width: 100%;
        }

        .fire-btn:hover {
            transform: translateY(-2px);
            opacity: 0.95;
        }

        .feedback-line {
            font-family: var(--font-mono);
            text-align: center;
            font-size: 0.95rem;
            font-weight: 700;
            min-height: 24px;
            letter-spacing: 0.5px;
            margin-top: 10px;
        }

        .text-success { color: var(--accent-green); }
        .text-error { color: var(--accent-red); }

        .screen-center {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            text-align: center;
            padding: 10px 0;
        }

        .primary-btn {
            background: var(--accent-teal);
            color: #00201a;
            border: none;
            padding: 14px 40px;
            font-family: var(--font-display);
            font-size: 1rem;
            font-weight: 700;
            text-transform: uppercase;
            letter-spacing: 1px;
            cursor: pointer;
            margin-top: 20px;
            border-radius: 6px;
            box-shadow: 0 4px 16px var(--glow-color);
        }

        .brief-box {
            background: var(--card-bg);
            border: 1px solid var(--border-color);
            padding: 22px 28px;
            text-align: left;
            margin: 20px 0;
            max-width: 680px;
            line-height: 1.7;
            font-size: 1rem;
            border-radius: 8px;
        }

        .brief-box ul { padding-left: 20px; }
        .brief-box li { margin-bottom: 8px; }

        footer {
            margin-top: 20px;
            font-family: var(--font-mono);
            font-size: 0.8rem;
            color: var(--text-secondary);
            text-align: center;
        }